(i) Field of the Invention
This invention relates to a system and method for the preservation of timber. In particular, it relates to compositions for preserving wooden poles, thereby prolonging the service life of wooden poles partially buried in the ground by treatment either before or after they are so partially buried and whether the poles are wet or dry.
(ii) Description of the Prior Art
The wood products with which the present invention is concerned are materials which are to have low aesthetic considerations, (e.g. foundation piles, poles, posts and fences, ties, marina structures, high-way and bridge construction, laminated systems for exterior use, and cooling towers. Such compositions and treatment procedures are designed to provide protection not only during the storage and the handling of the timber but also to provide protection during the final use of the timber. It also relates to the treated wood products so formed.
A piece of timber, due to the manner of its formation, possesses anisotropic structure which influence its properties and behaviour. To overcome and minimize these disadvantages a number of specific problems exist: the wood must be protected against degrading environmental factors (namely, moisture cycling, photodegradation and biological attack; the dimensional stability with respect to moisture cycling must be improved; photodegradation due to sunlight might be minimized; the resistance to biological attack (fungus) must be improved; and extractives which adversely affect the protective properties of coatings must be sealed within the wood.
Protective systems should impart not only protection against biological degradation, but also considerable weather resistance. The system should provide weather resistance with enhanced fire resistance.
Four classes of treatments are currently used in an attempt to meet these requirements. The first class is that of clear or pigmented penetrating systems which contain fungicides and water-repellent additives, e.g. polyethylene waxes and metal stearates in a non-aqueous solvent media. These treatments are deficient in that they must be repeated at regular intervals of about 1 to 2 years to provide a desired level of protection.
The second class is that of stains and sealers. These are normally synthetic resin solutions, usually pigmented and designed to penetrate the surface of the wood. These treatments as well are deficient, and should be repeated every one or two years in order to provide the required degree of protection.
The third class is that of paint systems. Such paint systems would normally consist of a primer and top coats. When well applied, these will provide protection from two to five years.
The fourth class is that of salt treatments. A number of salt treatments have been suggested, the most common of which are known as copper-chrome arsenate (CCA), acid-copper-chromate (ACC) and ammoniacal copper salts. Presently systems of this type are effective to provide relatively long term durability when applied by pressure impregnation techniques. While such systems are effective in preventing biological deterioration of wood and provide clean and paintable surfaces, they, however, suffer from several disadvantages. CCA preservatives have low stability under storage and processing conditions and penetration into wood is limited. ACC preservatives cannot penetrate refractory species but water repellency of wood treated by ACC is good. Ammoniacal copper salts provide extremely stable treating solutions and produce a treated wood product which is clean, in which the preservative penetrates deeply into the wood substance (particularly in the case of refractory species), but which provides only partial protection to the products against weathering. All systems provide products which are more or less colored; thus the natural appearance of wood is changed or covered by the colored preservative and so is unsuitable for aesthetrially pleasing materials. Furthermore, none of these systems provides protection against glowing combustion. The CCA systems are believed to become fixed in the wood by oxidation-reduction reactions associated with the chromic acid in the compositions and it is these same reactions which are believed adversely to affect stability and processing characteristics. Moreover, while providing a high level of protection against fungal attact, they provide only partial protection against weathering.
In addition, two main preserving systems are also used, namely, (1) creosote, and (2) pentachlorophenol in pole oil. These preserving systems are effective in (1) preventing fungal and insect attack on the wood substance; and (2) in preventing weathering of the timber. Both of these requirements are important where long life is required in wood exposed to the weather. However, these treatments suffer from several disadvantages. The most important of these is low cleanliness. Oil in these systems exudes to the surface making the wood unpleasant (dangerous) to handle, impossible to paint, and provides a surface which readily accumulates dirt.
Preservative systems which provide clean systems available at the present time are the oil-free pentachlorophenol systmes using liquified gas or highly chlorinated aliphatic hydrocarbons as a solvent and vehicle for pentachlorophenol. Data indicates that products produced by these processes are inferior in weather resistance to wood products impregnated by oil-borne preservatives. Moreover, neither of the above-mentioned systems protects the wood against glowing combustion.
Thus, each of the preserving systems mentioned above has disadvantages and these can be summarised as follows: The major disadvantage of the use of creosote and pentachlorophenol oil treatment is their low cleanliness and their lack of paintability. The major disadvantage of the use of copper-chrome-arsenate system is limited stability of the treating solution under processing conditions. The major disadvantage of the use of ammonical copper compounds is the lack of weathering resistance of the treated wood product. The major disadvantages of the use of oil-borne pentachlorophenol treatments is the lack of weathering properties relative to the creosote and pentachlorophenol-oil systems.
In the past, timbers, e.g. mooring piles were impregnated first with the water-borne inorganic mixed salts. Then, they were seasoned by kiln-drying, air seasoning, or some other method. They were then retreated with creosote. This procedure may take from several months to over a year. In Germany, it has been reported that the creosote treatment preceeds and the salt impregnation follows immediately or soon after. However, this introduces a problem of sludge formation, and disposal of contaminants which introduces yet another problem.
The main drawback of such double impregnation procedure is that processing is expensive because of the labour intensive operations of moving timbers to and from storage locations in a seasoning yard, and the delay in processing limited by the rate of moisture lost during seasoning. Also the creosote and water-borne solutions must be stored separately to avoid sludging problems. In any case, a certain amount of sludge does form because the solutions are used in tandem during processing.
It is frequently necessary to preserve timber products (against fungal attack, and marine borers) with two immiscible preservatives, i.e. creosote and inorganic salts. The reason is that neither creosote nor the inorganic salts (e.g. copper arsenate) are adequate to protect the timber when used alone.
Contemporary systems for heavy duty preservation of timber (e.g. as utility poles, piles, posts, bridge beams, lumber, etc.) frequently employed pentachlorophenol (PCP) as a reliable heavy duty preservative. Application to leave a clean surface involves processes like CELLON (trademark) LPG impregnation or the methylene chloride solvent treatment to drive the PCP into the wood providing a reasonably clean surface requiring no seasoning. However material treated with PCP by these processes, suffers from certain disadvantages, e.g. loss of PCP from wood sublimination and low water repellency and weather resistance. Both disadvantages result in lowering of service life when compared with wood treated by the older conventional PCP-oil-borne systems. This also results in limitations to use of the treated wood in closed poorly ventilated areas e.g. basements. The PCP-oil-borne systems have the major disadvantages of wood discoloration, oily unpaintible surfaces, stickiness and dirt retention.
These disadvantages (using the so-called clean processes) can be partially solved by raising the amount of preservative incorporated into the wood thus retaining the concentration level above or close to the effective threshold value enven after loss of some preservative, resulting in an acceptable service life. Adequate water-repellency and PCP retention, and elimination of the health hazard due to vapours of PCP, can be realized by additional painting or top-coating of the wood surface. Such additional treatments (use of excess PCP and/or top-coating) considerably increase the cost of the treated wood and in some places are not economical.
Telephone communication poles, and wooden power transmission poles will decay in line service (particularly at the ground/air interface) unless protected with wood preservatives. Generally, for a long service life (about 50 years or more), the poles are pressure impregnated with wood preservatives. These preservatives often lose effectiveness over a period of about 25 to about 35 years, generally in the groundline region (i.e. the ground/air interface) where conditions for leaching microbial activity and slow movement of preservative to the surrounding soil deplete the preservatives to ineffective levels. It is much more economical to apply a remedial form of preservative treatment to replenish the toxicity required at the groundline region than to replace the old poles with new impregnated ones. Poles which are given such remedial treatment with presently available preservatives are expected to last from about 5 to 15 years longer than if they had been left untreated. Hence, the groundline treatment must be repeated at about 5 to about 15 year intervals.
The need for prolonging the service life of existing poles is most urgent. Because many users of such poles cannot meet the demand for new pole requirements, existing poles must consequently be so improved that they will not require early replacement. This, in turn, means that the need for an improved form of groundline preservative is therefore urgently required.
A number of preservative mastics, or paste-type chemical formulations for groundline treatment exist. Most of these formulations contain pentachlorophenol in a suitable solvent, and non-leach resistant additives e.g., sodium fluoride and borax. Such formulations are generally applied to the groundline areas of utility poles in the form of bandages. However, since pentachlorophenol has been in short supply for the past few years and since the shortage may continue in the future, an alternative preservative is desirable. On the other hand, the non-leach resistant chemicals, when used alone, have a short life, and have been found not to be economically favourable.
While pentachlorophenol is very leach resistant, the rate of penetration of these systems is very slow, often requiring more than about 5 years for the toxic pentachlorophenol system to penetrate to about 11/2 inch depth, It is believed that the pentachlorophenol bandages lose some of their effectiveness after about 10 to about 15 years following treatments, and that retreatments may be necessary at a maximum of about 15 year intervals. On the other hand, while sodium fluoride penetrates rapidly, the levels of retention are very often too low to be effective.
Pentachlorophenol, the main component of the above-described groundline preservatives, is oil soluble and is carried in solvents, e.g. grease, thickened oil base, etc. Consequently, the system is not essentially compatible with wet wood, i.e. wood which has water which is considerably above the fibre saturation point. A very high percentage of poles are wet at the butt ends where effective treatment is required. It has also been found that the toxic components in many of the commercial formulations of groundline bandage preservatives do not penetrate the entire sapwood depth in poles. Consequently, it is believed that suitable groundline treatment of poles may extend their service life by about 2 to 5 years.
A soluble borate, namely, sodium tetraborate in water has been used in "pressure-diffusion" treatments in Australia. Such process consists of impregnating round material with a high concentration of the borate in an abbreviated schedule (in the retort) and then stacking the material to allow deeper penetration by diffusion. However, this technique suffers the disadvantage that an expensive pressure system is necessary.
For maximum protection of timber from biodegradation, or marine organisms, it has been suggested that wood be treated in two stages. First it should be treated with an arsenical preservative, and subsequently (after a seasoning period) with creosote, or other suitable oil-borne preservative. These water-soluble arsenical salts, and either creosote, or an oil soluble preservative are deposited (impregnated) in the wood to be protected. It is also common practice to preserve timbers for use in marine structures for coastal locations by a two step operation. Arsenic salts are impregnated first, and after a period of seasoning (usually several months outdoors), the creosote is impregnated. Deposits of both creosote and arsenic salts are specified at high retentions, i.e. creosote at about 20 pounds per cubic foot (pcf), and arsenic at about 1.0 pcf. This labour intensive movement of timber into the yard for double periods of seasoning is obviously disadvantageous.
The present limitation is the requirement for the seasoning which may be conducted either by stacking in a storage yard, and atmospheric evaporation of the moisture, or by artificial seasoning in the treating retort. The artificial seasoning process can be completed within about 18 to about 30 hours by steaming or boiling under vacuum procedure carried out in the treating retort.
In the treating of timber it is self evident that the greater the penetration of the treating agent into the wood, the better the preservation. It has generally been the practice to treat the timber in two stages--first with water borne salts and, following a seasoning period (usually several months), then with an oil-borne component, or creosote.
In the area of "oil-borne preservatives" a breakthrough was made when new preservative carriers were developed which dissolved lipophilic preservatives adequately. Commonly, two solvents are used in North America, methylene dichloride and so-called liquefied petroleum gases. They penetrate into wood well and are recoverable from wood after treatment. Methylene dichloride is used in Canada also for treatment of spruce which it penetrates satisfactorily.
In the field of water-borne preservatives there was a similar need: to find a suitable solvent for spruce with good penetration characteristics.
It has been found that ponding or continuous spraying for a few months increases preservative penetrability of spruce so that a full sapwood penetration can be obtained by a standard pressure process. White spruce poles may be penetrated deeply and uniformly with creosote throughout the 11/2-inch sapwood by standard impregnation processes when conditioned by fresh-water ponding. Ponding now is carried out by floating debarked logs in fresh water for about 12 weeks at a mean temperature of about 65.degree. F.
When creosote, or petroleum oils are mixed with ammonium hydroxide solution and agitated for thorough blending, almost immediate separation takes place upon storage of the mixture.
Water soluble phases and oil phases when mixed together are not miscible, generally separate rapidly, and frequently tend to produce sludges (which could not be used in wood preservation).
Arsenical creosote (AC) is well known. R. Johnson in the publication in a paper entitled "THE INCORPORATION OF ARSENIC IN CREOSOTE, PART 3* STABILITY OF ARSENICAL CREOSOTE IN THE PRESENCE OF WATER IN WOOD that equal amounts of arsenic can be incorporated with dry creosote or with creosote saturated with water. Heating of As.sub.2 O.sub.3 with creosote at about 90.degree. C., for about 4 hr. produces an arsenical creosote (AC) with a maximum arsenic content of about 0.5 percent As.sub.2 O.sub.3. Higher temperatures increase the incorporation of As.sub.2 O.sub.3 to a maximum of about 0.75 percent at about 200.degree. C. and about 0.94 percent at about 220.degree. C., but prelonged refluxing reduces the arsenical contents. The arsenical creosote was a heterogeneous mixture, not well suited for uniform treatment of timber.
A paper in the Forest Products Journal, Vol. 20, No. 11, November 1970 by M. P. Levi et al entitled "Distribution and Effectiveness in Pinus Sp. of a Water Repellent Additive for Water-Borne Wood Preservatives" discusses the development of a water repellent additive for use with water-borne CCA preservatives to overcome the deficiency of prevention of weathering degradation.
Ammonical copper arsenite compositions are presently being used as preservatives. Zinc arsenite compositions are also presently being used as preservatives. Zinc arsenate, zinc arsenite, and zinc phosphate can all be applied from an acetic acid solution and, on drying, the salt is insoluble and fixed in the wood. However, in all of these cases, the weather resistance of the treated wood is not significantly improved.
U.S. Pat. No. 1,145,186 patented July 6, 1915 by Eberhard provided an anticorrosive paint which was based on the fact that certain compounds of chromium soluble in oil or fat respectively, possess very valuable qualities for prevention of rust. These compounds have the same degree of oxidation as chromic acid, or an ethereal solution of chromic acid as well as of perchromic acid and also chromium phosphate dissolved in oil or fat. If linseed oil or varnish is acted upon in a suitable manner by chromyl chloride, and if a violent reaction is prevented, a clear viscid greenish purple oil, or a varnish respectively is obtained which proves to be highly valuable as a rust preventing means. To prevent an excessive action of chromyl chloride upon oils, varnishes, and the like, toluene, nitro-benzene, chloroform, aniline or similar hydrocarbons as well as bisulphide of carbon may be used.
U.S. Pat. No. 1,456,509 issued to A. Mai on May 29, 1923, taught that arsenic acids, sulfides of arsenic, Schweinfurt or Paris green and other arsenical compounds or mixtures may be brought in to solution to a large extent by the action of halogen inorganic substances or compounds with easily detachable halogen atoms, as, bromine or tribromide of arsenic, or with organic halogenical compounds or aliphatic or aromatic bodies containing several substituted halogen atoms, as phthalyl chloride, tribromacetic acid, tetrachloronaphthalene or mixtures thereof, in most of the organic solvents, e.g., acetone, ether, alcohol, amylacetate, ethylacetate, benzine, benzol, tar-oils, petroleum, etc., or in mixtures of any of these substances. Solutions of this kind have been said to have the advantage that they completely penetrate the wood in one single process, that they are not washed out and that according to the solvent selected they unite in themselves insecticidal and fungicidal qualities. Moreover, they have been said to permit the solution of inorganic preservatives, for example, naphthalene, anthracene, phenols, nitro-compounds, alkaloid salts, resins and the like, with the sole exception of the free bases; they are also solvents of sulfur.
It has still further been proposed (see U.S. Pat. No. 1,942,977 issued Jan. 9, 1934 to E. E. M. Payne) to treat wood products with a solution of one or more ammonium phosphates and then with a solution containing acid phosphates of magnesium and zinc, in order to precipitate an insoluble phosphate within the cell structure of the material, thereby to improve the color of the materials and to render the treated material resistant to fire.
Copper and zinc-containing fungicides which have been proposed (see U.S. Pat. No. 2,414,661 issued Jan. 21, 1947 to A. A. Nikitin), where prepared by precipitation of a zinc salt and a copper salt from an aqueous solution with an alkali solution containing soya bean protein, or soaps of fatty acids.
Fungicides, which have been proposed for cellulosic materials, (see U.S. Pat. No. 2,423,619 issued July 8, 1947 to L. Roon) comprise copper soaps formed in situ from an aqueous solution of copper salts and aqueous ammonia by reaction with fatty acids.
It has also been proposed to provide water and fire-resistant coatings on wood, (see U.S. Pat. No. 2,530,453 issued Nov. 21, 1950 to H. R. Frisch) by the use of zinc orthophosphate or zinc orthoarsenate compositions applied as a concentrated solution in aqueous ammonia.
It has been proposed, (see U.S. Pat. No. 2,722,263 issued Nov. 27, 1956 to C. C. Yeager) to use a compound having a high fungicidal activity in wood, which compound is a metal resin ammonium phenoxide-complex metal carboxylic acid soap compound, prepared by reacting a resin ammonium phenoxide with a water-soluble salt of a metal capable of forming a complex with ammonia.
It has been further proposed, (see U.S. Pat. No. 2,768,910 issued Oct. 30, 1956 to J. Krzikalla and O. Lissner) to improve the hardness, compressive strength, hydroscopicity and liability to swelling of wood by impregnating the wood with an aqueous ammoniacal solution of polycarboxylic acid containing at least six carbon atoms.
U.S. Pat. No. 2,875,020 issued Feb. 24, 1959 to R. G. Ring provides a wood preservative method and package including a porous fibrous oil and water permeable sheet, e.g. a porous fibrous material for example, fibrics and felted mats of vegetable fibres or glass fibre; a layer on one side only of the sheet of an inert, oil base carrier of grease-like consistency containing at least 2% pentachlorophenol, and a synthetic reservoir oil and water impervious film completely enclosing the sheet and layer, e.g. a sleeve of polyethylene, polyvinyl compounds, etc. Such procedure is labour intensive and undesirable.
U.S. Pat. No. 2,939,704 issued June 7, 1960 to C. E. Wilkinson provides a composition including a suitable asphalt base, cut back with a volatile diluent, as well as an inorganic filler consisting essentially of fine asbestos fibres, fine mica, fine vermiculate or fine alkali metal tetraborate. This suffers the disadvantage of lack of compatibility of the organic component (the asphalt), i.e. the most effective preservative constituent, with wet wood.
It has also been proposed, (see U.S. Pat. No. 3,007,844 issued Nov. 7, 1961 to W. O. Schuly) to use a composition comprising a heavy metal ion, borate ions and chromate ions as an impregnating agent for the preservation of wood.
It has further been proposed, (see U.S. Pat. No. 3,105,773 issued Oct. 1, 1963 to S. Frank and D. C. Wehner) to preserve wood by imparting pesticidal and anti-thallophytic properties thereby by first impregnating the wood with a water-soluble heavy metal salt, and with an acrylic polymer solution.
U.S. Pat. No. 3,376,144 issued Apr. 2, 1968 to R. E. Strutz provides a wood preservative composition thickened with a combination of a microcrystalline wax, water soluble non-ionic surfactant, and water, combined with a mixture of an organic wood preservative liquid and an alkaline inorganic alkali metal salt. This composition suffers the disadvantage of a low level of retention.
U.S. Pat. No. 3,390,951 issued July 2, 1968 to J. H. Finger et al provides a method of strengthening, preserving and extending the life of wooden poles by applying a metal band to the pole surrounding the zone of weakness with a fibrous resin impregnated material, and connecting tension means to the pole above the upper band means and below the lower band means and extending therebetween. This procedure suffers the disadvantage of being too labour intensive and provides a separate heterogenous addition to the pole.
U.S. Pat. No. 3,409,388 issued Nov. 5, 1968 to R. F. Nelson provides a method for preserving wooden poles by applying a bandage which is an elongated tube of preservative impermeable water soluble material, to spaced areas of the pole and dissolving the protective film to permit direct contact between the preservative and the pole. This suffers the disadvantage of low level of retention and of not providing optimum times of contact of the wrapped preservative with the wood.
U.S. Pat. No. 3,764,377 patented Oct. 9, 1973 by W. E. Keys provided a wood treating composition containing a novel arsenic compound that is compatible with creosote, and includes the toxic qualities of arsenic compounds as well as those of creosote. The novel organic arsenic compound is formed by the reaction of arsenous oxide (AS.sub.2 O.sub.3) with N,N,N',N'-tetrakis(2-hydroxypropyl)ethylene diamine, and has the general structure ##STR1##
It has also been proposed, [see British Patent No. 1,220,281 published Jan. 27, 1971 in the name of Hickson's Timber Impregnation Co. (G.B.) Ltd.] to treat wood with an aqueous emulsion containing an aqueous solution of a wood preservative composition based on hexavalent chromium, a water-insoluble insecticide in a liquid hydrocarbon solvent, and a non-ionic surface active agent. The emulsion is used by impregnation of the wood by means of a pressure process, to provide protection against fungal attack and against a variety of insects.
Canadian Patent No. 515,610 provides a wood treating composition consisting essentially of a material selected from the group consisting of:
water miscible polyhydric alcohols having from 2 to 6 hydroxyl groups; solutions of boric acid in water miscible polyhydric alcohols having from 2 to 6 hydroxyl groups; solutions of an alkali metal borate in water miscible polyhydric alcohols having from 2 to 6 hydroxyl groups; boric acid esters of water miscible polyhydric alcohols having from 2 to 6 hydroxyl groups; and mixtures thereof contained in an impregnant selected from the group consisting of the tars and creosotes. PA1 arsenic oxide (As.sup.III): 1.2 parts by weight PA1 zinc oxide: 3.6 parts by weight PA1 NH.sub.4 HCO.sub.3 : 4.0 parts by weight aqueous ammonia solution (28% NH.sub.3, 20 ml in 100 ml H.sub.2 O): 91.0 parts by weight PA1 arsenic oxide (As.sup.v): 1.4 parts by weight PA1 zinc oxide: 3.6 parts by weight PA1 HN.sub.4 HCO.sub.3 : 4.1 parts by weight PA1 aqueous ammonia solution (28% NH.sub.3, 20 ml in 100 ml H.sub.2 O): 91.9 parts by weight PA1 arsenic oxide (As.sup.v): 1.4 parts by weight PA1 copper oxide: 1.8 parts by weight PA1 zinc oxide: 1.0 parts by weight PA1 annonium bicarbonate: 2.4 parts by weight PA1 arsenic oxide (As.sup.v): 1.4 parts by weight PA1 copper oxide: 1.2 parts by weight PA1 zinc oxide: 1.8 parts by weight PA1 aqueous ammonia solution (28% NH.sub.3, 22.5 ml in 100 ml H.sub.2 O): 95.6 parts by weight PA1 arsenic oxide (As.sup.v): 1.4 parts by weight PA1 copper oxide: 0.6 parts by weight PA1 zinc oxide: 2.7 parts by weight PA1 NH.sub.4 HCO.sub.3 : 3.5 parts by weight PA1 aqueous ammonia solution (28% NH.sub.3, 21.2 ml in 100 ml H.sub.2 O): 91.8 parts by weight PA1 zinc meta arsenite: 1.5 parts by weight PA1 zinc carbonate: 4.5 parts by weight PA1 decanoic acid: 3 parts by weight PA1 aqueous ammonia (5% ammonia in water): 91 parts by weight PA1 copper arsenate: 3 parts by weight PA1 copper carbonate: 3 parts by weight PA1 organic additive as e.g. decanoic acid: 2 parts by weight PA1 aqueous ammonia (5% ammonia in water): 92 parts by weight PA1 zinc arsenate: 4 parts by weight PA1 nonanoic acid: 2 parts by weight PA1 zinc carbonate: 1 part by weight PA1 aqueous ammonia solution (7%): 93 parts by weight PA1 zinc arsenate: 4.5 parts by weight PA1 zinc carbonate: 2.0 parts by weight PA1 monododecyl phosphate: 0.2 parts by weight PA1 aqueous ammonia solution (7%): 93.3 parts by weight PA1 zinc arsenate: 1 part by weight PA1 decanoic acid: 3 parts by weight PA1 zinc carbonate: 3 parts by weight PA1 aqueous ammnonia solution (10%): 93 parts by weight PA1 zinc arsenate: 1 part by weight PA1 zinc oxide: 5 parts by weight PA1 ammonium carbonate: 2 parts by weight PA1 dibutyl phosphate: 0.2 parts by weight PA1 aqueous ammonia solution (10%): 91.8 parts by weight PA1 copper carbonate: 1 part by weight PA1 copper arsenate: 1 part by weight PA1 lauric acid: 0.5 parts by weight PA1 aqueous ammonia solution (5): 98.5 parts by weight PA1 copper arsenate: 3 parts by weight PA1 decanoic acid: 3 parts by weight PA1 aqueous ammonia solution (7%): 94 parts by weight PA1 copper carbonate: 1 part by weight PA1 copper arsenite: 1 part by weight: PA1 nonanoic acid: 2 parts by weight PA1 aqueous ammonia solution (7%): 96 parts by weight PA1 copper carbonate: 1 part by weight PA1 copper arsenite: 2 parts by weight PA1 decanoic acid: 3 parts by weight PA1 aqueous ammonia solution (7%): 94 parts by weight PA1 arsenic oxide (III): 1.22 parts by weight PA1 zinc oxide: 3.57 parts by weight PA1 NH.sub.4 HCO.sub.3 : 4.12 parts by weight PA1 aqueous ammonia (28% NH.sub.3, 20 ml in 100 ml water): 91 parts by weight PA1 arsenic oxide (V): 1.42 parts by weight PA1 zinc oxide: 3.57 parts by weight PA1 NH.sub.4 HCO.sub.3 : 4.12 parts by weight PA1 aqueous ammonia (28% NH.sub.3, 20 ml in 100 ml water): 90 parts by weight PA1 arsenic oxide: 1.42 parts by weight PA1 copper oxide: 2.43 parts by weight PA1 NH.sub.4 HCO.sub.3 : 1.80 parts by weight PA1 aqueous ammonia (28% NH.sub.3, 25 ml in 10 ml water): 94 parts by weight PA1 copper oxide: 2.4 parts by weight PA1 NH.sub.4 HCO.sub.3 : 1.8 parts by weight PA1 aqueous ammonia (28% NH.sub.3, 25 ml in 100 ml water): 94.4 parts by weight PA1 arsenic oxide (III): 1.2 parts by weight PA1 zinc oxide: 3.6 parts by weight PA1 NH.sub.4 HCO.sub.3 : 4.2 parts by weight PA1 aqueous ammonia (28% NH.sub.3, 20 ml in 100 ml water): 91 parts by weight PA1 arsenic oxide (V): 1.4 parts by weight PA1 zinc oxide: 3.5 parts by weight PA1 NH.sub.4 HCO.sub.3 : 4.1 parts by weight PA1 aqueous ammonia (28% NH.sub.3, 20 ml in 100 ml water): 90 parts by weight PA1 16.04 g CrO.sub.3 PA1 6.24 g CuO PA1 11.48 g As.sub.2 O.sub.5 filled up to 1000 ml with H.sub.2 O; PA1 3.4 percent salts on oxide basis; PA1 pH=1.34 PA1 35 g CuCo.sub.3.Cu(OH).sub.2 PA1 18 g NH.sub.4 HCO.sub.3 PA1 250 ml NH.sub.4 OH (26% NH.sub.3) PA1 20 g H.sub.3 A.sub.5 O.sub.4 (71% As.sub.2 O.sub.5) PA1 filled up to 1000 ml with H.sub.2 O; PA1 3.9 percent salts on oxide basis PA1 35.7 g ZnO `41.2 g Nh.sub.4 HCO.sub.3 PA1 200 ml H.sub.3 A.sub.5 O.sub.4 (71% As.sub.2 O.sub.3) PA1 diluted 1+4 by H.sub.2 O; PA1 5.0 percent salts on oxide basis
Canadian Patent No. 568,393 issued Jan. 6, 1959 to Bror O. Hager proposed to provide an agent for the preservation of wood including an aqueous ammoniacal solution of an amine-forming metal of the group consisting of copper, zinc, nickel, cobalt, cadmium and silver, and dissolved carbon dioxide of a content of at least two-thirds of the metal content. This composition is far too dilute to be used for groundline treatment. The same patentee, in Canadian Patent No. 960,959 issued Jan. 14, 1975, provided a composition consisting essentially of (1) a metal compound selected from the group consisting of the oxides, hydroxides, and carbonates of copper, zinc, nickel, cadmium and cobalt, and (2) a fatty acid having from 6 to 12 carbon atoms per molecule, dissolved in (3) an annomiacal water solution. Both these compositions suffer the disadvantage that they do not have optimum high water repellency, optimum low water uptake, optimum fast and high preservative penetration, and optimum resistance to arsenic leaching.
Canadian Patent No. 978,474 issued Nov. 25, 1975 naming Michael R. Clarke and Jaromir R. Rak as inventors, provides a dilute aqueous composition comprising a normally water-insoluble compound selected from zinc arsenate, zinc arsenite, copper arsenate, copper arsenite or mixtures thereof, a water repellent component, including a carbonate or bicarbonate and sufficient ammonia to dissolve the normally water-insoluble compound. This composition, while it is very useful, is too dilute to be used to preserve wooden poles at the groundline in the form of bandages. Also, the composition is not sufficiently compatible with wet poles.
Canadian Patent NO. 1,001,948 issued Dec. 21, 1976 naming Jaromir Rak as inventor provides a wood preservative composition imparting a clean surface and good service life to the wood substrate, comprising (a) an organic wood preservative agent, i.e. pentachlorophenol (as primary preservative); (b) a hydrophobic agent selected from fatty acids and their esters, fatty alcohols and various waxes, suitably having at least ten carbon atoms in the longest chain in the molecule; (c) an amorphous polymer; and (d) an organic solvent for (a), (b) and (c).
Canadian Patent No. 1,058,353 issued July 17, 1979 naming John Krzyzewski, as inventor provides a thickened ammonia-base wood treating composition for application as a covered layer to a wood surface, the composition comprising: (A) a preservative component which is one of (i) a normally water-insoluble salt selected from the group consisting of zinc arsenate, zinc arsenite, copper arsenate, copper arsenite and mixtures thereof; (ii) an ammonia-soluble salt selected from the group consisting of copper borate, zinc borate or mixtures thereof, and copper chromate, zinc chromate or mixtures thereof; or (iii) an ammonia dispersible organometallic compound selected from the group consisting of copper naphthenate, zinc naphthenate or mixtures thereof, copper-8-quinolinolate, zinc-8-quinolinelate or mixtures thereof, or tributyltin oxide; and (iv) sufficient aqueous ammonia, in a concentration of about 1 to about 28% by weight NH.sub.3 to solubilize the normally water-insoluble salt (i), or the ammonia-soluble salt (ii), or to disperse the organometallic compound (iii); and (B) a sufficient amount of thickener component selected from the group consisting of: (v) (a) a saturated fatty acid of 12 to 22 carbon atoms; (b) an unsaturated fatty acid of 12 to 22 carbon atoms; (c) a copper, zinc, sodium, potash, or amine salt of a saturated fatty acid of 12 to 22 carbon atoms; or (e) mixtures thereof; (vi) (a) asbestos screenings; (b) natural serpentine fibrous fragments; (c) mica flakes; (d) adipic acid plus asbestos screenings; (e) adipic acid plus natural serpentine fibrous fragments; or (f) adipic plus mica flakes; (vii) a mastic of (a) a petroleum fraction selected from oils and greases with one of (b) asbestos screenings; (c) natural serpentine fibrous fragments; (d) mica flakes; (e) adipic acid plus asbestos screenings; (f) adipic acid plus natural serpentine fibrous fragments; or (g) adipic acid plus mica flakes; and (viii) a metallic soap selected from an insoluble soap of naphthenic acid , octoic acid, 2-ethylhexoid acid, rosin acids or tall oil acids, with aluminum, calcium, cadmium, cobalt, copper, iron, lead, manganese, nickel, tin or zinc; to provide a thickened composition having a viscosity of at least 30 poises, and desirably to provide one composition of about 30 to about 120 poises, and another composition of about 250 to about 300 poises, the viscosity in poises being measured by a Brookfield Viscometer at 25.degree. C.